EP0208422B1 - Process for the manufacture of monopotassium phosphate - Google Patents
Process for the manufacture of monopotassium phosphate Download PDFInfo
- Publication number
- EP0208422B1 EP0208422B1 EP86304442A EP86304442A EP0208422B1 EP 0208422 B1 EP0208422 B1 EP 0208422B1 EP 86304442 A EP86304442 A EP 86304442A EP 86304442 A EP86304442 A EP 86304442A EP 0208422 B1 EP0208422 B1 EP 0208422B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- phosphate
- monopotassium
- phosphoric acid
- filtrate
- process according
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- LWIHDJKSTIGBAC-UHFFFAOYSA-K potassium phosphate Substances [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 title claims abstract description 58
- 229910000402 monopotassium phosphate Inorganic materials 0.000 title claims abstract description 50
- 235000019796 monopotassium phosphate Nutrition 0.000 title claims abstract description 50
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 title claims abstract description 50
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 11
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 86
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 43
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000000706 filtrate Substances 0.000 claims abstract description 33
- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 claims abstract description 27
- 239000000203 mixture Substances 0.000 claims abstract description 25
- 239000002367 phosphate rock Substances 0.000 claims abstract description 24
- 239000000292 calcium oxide Substances 0.000 claims abstract description 21
- CHKVPAROMQMJNQ-UHFFFAOYSA-M potassium bisulfate Chemical compound [K+].OS([O-])(=O)=O CHKVPAROMQMJNQ-UHFFFAOYSA-M 0.000 claims abstract description 17
- 239000003960 organic solvent Substances 0.000 claims abstract description 9
- 229910019142 PO4 Inorganic materials 0.000 claims abstract description 7
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims abstract description 7
- 239000010452 phosphate Substances 0.000 claims abstract description 7
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 6
- 239000012535 impurity Substances 0.000 claims abstract description 6
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims abstract description 5
- 239000000920 calcium hydroxide Substances 0.000 claims abstract description 5
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims abstract description 5
- 150000001875 compounds Chemical class 0.000 claims abstract description 5
- 239000000470 constituent Substances 0.000 claims abstract description 5
- 229910052751 metal Inorganic materials 0.000 claims abstract description 5
- 239000002184 metal Substances 0.000 claims abstract description 5
- 239000005416 organic matter Substances 0.000 claims abstract description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims abstract description 3
- 239000011575 calcium Substances 0.000 claims abstract description 3
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 3
- 150000002222 fluorine compounds Chemical class 0.000 claims abstract 2
- 239000001506 calcium phosphate Substances 0.000 claims description 38
- 235000019739 Dicalciumphosphate Nutrition 0.000 claims description 32
- 229910000390 dicalcium phosphate Inorganic materials 0.000 claims description 32
- 229940038472 dicalcium phosphate Drugs 0.000 claims description 32
- 238000006243 chemical reaction Methods 0.000 claims description 22
- 239000002002 slurry Substances 0.000 claims description 12
- 235000011132 calcium sulphate Nutrition 0.000 claims description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 10
- 239000010440 gypsum Substances 0.000 claims description 9
- 229910052602 gypsum Inorganic materials 0.000 claims description 9
- 238000006386 neutralization reaction Methods 0.000 claims description 9
- 239000001117 sulphuric acid Substances 0.000 claims description 7
- 235000011149 sulphuric acid Nutrition 0.000 claims description 7
- 239000001175 calcium sulphate Substances 0.000 claims description 6
- ZPWVASYFFYYZEW-UHFFFAOYSA-L dipotassium hydrogen phosphate Chemical compound [K+].[K+].OP([O-])([O-])=O ZPWVASYFFYYZEW-UHFFFAOYSA-L 0.000 claims description 5
- 235000019797 dipotassium phosphate Nutrition 0.000 claims description 4
- 229910000396 dipotassium phosphate Inorganic materials 0.000 claims description 4
- 238000011065 in-situ storage Methods 0.000 claims description 4
- 239000007795 chemical reaction product Substances 0.000 claims description 3
- 230000003472 neutralizing effect Effects 0.000 claims description 2
- 235000011007 phosphoric acid Nutrition 0.000 claims description 2
- NEFBYIFKOOEVPA-UHFFFAOYSA-K dicalcium phosphate Chemical compound [Ca+2].[Ca+2].[O-]P([O-])([O-])=O NEFBYIFKOOEVPA-UHFFFAOYSA-K 0.000 claims 6
- 235000012255 calcium oxide Nutrition 0.000 abstract description 14
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 abstract description 8
- 235000011116 calcium hydroxide Nutrition 0.000 abstract description 2
- 235000010216 calcium carbonate Nutrition 0.000 abstract 1
- FUFJGUQYACFECW-UHFFFAOYSA-L calcium hydrogenphosphate Chemical compound [Ca+2].OP([O-])([O-])=O FUFJGUQYACFECW-UHFFFAOYSA-L 0.000 description 27
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 16
- 238000004458 analytical method Methods 0.000 description 13
- 239000000243 solution Substances 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 239000012065 filter cake Substances 0.000 description 9
- 239000000047 product Substances 0.000 description 9
- 239000003337 fertilizer Substances 0.000 description 8
- 239000001103 potassium chloride Substances 0.000 description 8
- 235000011164 potassium chloride Nutrition 0.000 description 8
- 239000013078 crystal Substances 0.000 description 7
- 238000001914 filtration Methods 0.000 description 7
- YYRMJZQKEFZXMX-UHFFFAOYSA-L calcium bis(dihydrogenphosphate) Chemical compound [Ca+2].OP(O)([O-])=O.OP(O)([O-])=O YYRMJZQKEFZXMX-UHFFFAOYSA-L 0.000 description 5
- 239000003153 chemical reaction reagent Substances 0.000 description 5
- 238000002425 crystallisation Methods 0.000 description 5
- 230000008025 crystallization Effects 0.000 description 5
- 235000019691 monocalcium phosphate Nutrition 0.000 description 5
- 229910000150 monocalcium phosphate Inorganic materials 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- OTYBMLCTZGSZBG-UHFFFAOYSA-L potassium sulfate Chemical compound [K+].[K+].[O-]S([O-])(=O)=O OTYBMLCTZGSZBG-UHFFFAOYSA-L 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 235000013305 food Nutrition 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- OQZCJRJRGMMSGK-UHFFFAOYSA-M potassium metaphosphate Chemical compound [K+].[O-]P(=O)=O OQZCJRJRGMMSGK-UHFFFAOYSA-M 0.000 description 2
- 229940099402 potassium metaphosphate Drugs 0.000 description 2
- 229910000160 potassium phosphate Inorganic materials 0.000 description 2
- 235000011009 potassium phosphates Nutrition 0.000 description 2
- SDRZXZKXVBHREH-UHFFFAOYSA-M potassium;dihydrogen phosphate;phosphoric acid Chemical compound [K+].OP(O)(O)=O.OP(O)([O-])=O SDRZXZKXVBHREH-UHFFFAOYSA-M 0.000 description 2
- 239000011541 reaction mixture Substances 0.000 description 2
- 229910021653 sulphate ion Inorganic materials 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- NPYPAHLBTDXSSS-UHFFFAOYSA-N Potassium ion Chemical compound [K+] NPYPAHLBTDXSSS-UHFFFAOYSA-N 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- LFVGISIMTYGQHF-UHFFFAOYSA-N ammonium dihydrogen phosphate Chemical compound [NH4+].OP(O)([O-])=O LFVGISIMTYGQHF-UHFFFAOYSA-N 0.000 description 1
- 229910000387 ammonium dihydrogen phosphate Inorganic materials 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- 229940043430 calcium compound Drugs 0.000 description 1
- 150000001674 calcium compounds Chemical class 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 229910000389 calcium phosphate Inorganic materials 0.000 description 1
- 235000011010 calcium phosphates Nutrition 0.000 description 1
- ZHZFKLKREFECML-UHFFFAOYSA-L calcium;sulfate;hydrate Chemical compound O.[Ca+2].[O-]S([O-])(=O)=O ZHZFKLKREFECML-UHFFFAOYSA-L 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- RBLGLDWTCZMLRW-UHFFFAOYSA-K dicalcium phosphate dihydrate Substances O.O.[Ca+2].[Ca+2].[O-]P([O-])([O-])=O RBLGLDWTCZMLRW-UHFFFAOYSA-K 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 150000004673 fluoride salts Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 125000005341 metaphosphate group Chemical group 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 235000019837 monoammonium phosphate Nutrition 0.000 description 1
- 239000006012 monoammonium phosphate Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 229910001414 potassium ion Inorganic materials 0.000 description 1
- 229910052939 potassium sulfate Inorganic materials 0.000 description 1
- 235000011151 potassium sulphates Nutrition 0.000 description 1
- 239000012047 saturated solution Substances 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/30—Alkali metal phosphates
- C01B25/301—Preparation from liquid orthophosphoric acid or from an acid solution or suspension of orthophosphates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/30—Alkali metal phosphates
- C01B25/301—Preparation from liquid orthophosphoric acid or from an acid solution or suspension of orthophosphates
- C01B25/303—Preparation from liquid orthophosphoric acid or from an acid solution or suspension of orthophosphates with elimination of impurities
Definitions
- the present invention relates to a new process for the manufacture of monopotassium phosphate. More particularly the present invention relates to a new process for the direct manufacture of pure monopotassium phosphate which does not involve the use of organic solvents.
- Monopotassium phosphate is considered a most valuable fertilizer because of its high content of both potassium and phosphate in an available form.
- the total plant food of this fertilizer is 86.8%, which is higher than most of the other known fertilizers.
- monopotassium phosphate possesses a very low salt index (8.4) compared with 46 for potassium sulfate, 116.3 for potassium chloride and 29.9 for monoammonium phosphate.
- Another important property of this fertilizer is its very high water solubility (26.6 g/100 g water at 25 degrees C). The significance of high water-solubility for the agricultural value of phosphate fertilizers was proven by field experiments and found especially important for crops with short growing seasons.
- Monopotassium phosphate was first prepared already in 1821, by the neutralization of phosphoric acid with a solution of potassium carbonate and crystallizing out the product.
- this method has only a theoretical interest and can not be considered applicable on a commercial scale for fertilizer purposes.
- Patents for the manufacture of monopotassium phosphate by heating potassium chloride with phosphoric acid, in various molecular proportions, whereby a double salt of monopotassium phosphate+phosphoric acid resulted. The phosphoric acid is removed by an organic solvent and thus the desired monopotassium phosphate is obtained.
- the temperature parameter for the reaction between the potassium chloride and phosphoric acid was fully investigated. It was found that at atmospheric pressure, temperatures above 160 degrees C are required for a complete conversion of K + to potassium monophosphate. However at temperatures above 200 degrees C, water insoluble potassium metaphosphate is produced and in most of the patents it is suggested not to surpass this temperature.
- US ⁇ A ⁇ 3697246 discloses a process wherein monopotassium phosphate is produced by the reaction of phosphate rock or a solubilized form thereof such as monocalcium phosphate, dicalcium phosphate etc., potassium bisulphate, a sufficient excess of sulphuric acid to drive the reaction to completion at 40 to 90°C and optionally fresh or recycled phosphoric acid. Precipitated calcium sulphate is filtered off and monopotassium phosphate is recovered from the filtrate by concentration and filtration or, more preferably, by extraction with an organic solvent.
- the present invention consists in a process for the manufacture of substantially pure monopotassium phosphate without the use of organic solvents which comprises the steps of:
- the preferred amount of phosphoric acid in step (a) should be in the range of 10 to 35% of the total P 2 0 5 present at the end of the step. Above 35% the process is still operable, but any excess above this value is actually a waste of P 2 0 5 .
- the concentration of the P 2 0 1 is not critical and can be selected in a very broad range. Using the above steps, the product obtained will not be accompanied by phosphoric acid (double salt monopotassium phosphate-phosphoric acid) as encountered in the prior art methods.
- One of the characteristics of the system in the present invention is the absence of monocalcium phosphate. This is a result of an excess of the sulphate ion which is present therein, which excludes the formation of monocalcium phosphate, due to the formation of the insoluble calcium sulphate.
- the excess of sulphate ion has also a beneficial effect on the generation of well-shaped crystals of gypsum with the consequence of their easy filtration, washing and separation.
- the starting reagent for the present invention is monopotassium sulphate. As is known, this salt is easily obtained in the reaction between potassium chloride and sulphuric acid. As appears from the reactions presented below, the reaction between potassium chloride and sulphuric acid occurs in two distinct steps:-
- the first reaction for the formation of monopotassium sulfate occurs smoothly and is much more easily performed (being exothermic) than the second one of dipotassium sulfate formation (which is endothermic).
- the proper conditions for the preparation of monopotassium sulfate are well known from the prior art, its preparation being not considered part of the present invention. As known, the temperatures at which it takes place are low enough to permit the use of corrosion-resistant plastics, thus reducing the capital costs.
- the temperatures involved in the process according to the present invention are in the range of between 40 to 100 degrees centigrade and preferably in the range of 60 to 80 degrees centigrade.
- the above relatively low temperature ranges exclude completely the possibility of co-producing the insoluble potassium phosphate, known under the name of potassium metaphosphate, which are obtained in the prior art methods based on the reaction between KCI and phosphoric acid.
- the prior art references are utilizing temperatures above 160 degrees centigrade and generally close to 200 degrees centigrade in order to complete the expulsion of HCI resulting in the reaction:
- the reaction with phosphate rock or dicalcium phosphate (or mixtures thereof) is carried out in two or more stages: in the first stage, the reaction occurs between monopotassium sulphate and part of the phosphate rock or dicalcium phosphate (or mixtures thereof) in the presence of phosphoric acid.
- the phosphoric acid may be added as such or produced in-situ from an additional amount of phosphate rock or dicalcium phosphate and sulphuric acid.
- the use of phosphoric acid produced in-situ has significant economic advantages in view of the improved filtration properties in the gypsum resulting therefrom.
- reaction products resulted from the first stage are reacted with a new portion of phosphate rock or dicalcium phosphate.
- An additional advantage of this embodiment is the fact that the gypsum formed thereby possesses improved filtration properties which enables its easy separation. Furthermore an appreciable amount of organic matter present in the phosphate rock will be also removed.
- step (a) In order to obtain a maximum conversion of the K + value into the monopotassium phosphate, it is suggested to carry out a desulphation of the solution resulting from step (a), prior to its neutralization. This can be accomplished by the reaction of said solution with calcium phosphate (as presented in the chemical reaction 5 given below). In this case the amount of phosphoric acid present in the system will be generally in the range of about 5 to 18% by wt P 2 0 5 . The result of this step will be that the solution entering to the neutralization will be substantially depleted from the sulfate ion, which is an additional advantage by increasing the conversion of the potassium ion into monopotassium phosphate.
- the second step of the process involves the neutralization of the filtrate obtained in step (a), said filtrate consisting of phosphoric acid and monopotassium phosphate.
- This neutralization is carried out either with calcium oxide (calcium hydroxide), calcium carbonate or other substances containing these compounds or any mixture thereof, depending on the availability of such reagents.
- the final pH of the neutralized solution should be in the range of 3 to 7 and preferably in the range of 3.5 to 5.
- the neutralization occurs also with the monopotassium phosphate producing dipotassium phosphate along dicalcium phosphate according to the following equation:
- the final neutralized product as obtained in this case will be an equimolar mixture of monopotassium phosphate and dipotassium phosphate along with the insoluble dicalcium phosphate which is filtered off. Part of the dicalcium phosphate resulted can be recycled to step (a) in the reaction with monopotassium sulfate, or with sulfuric acid in case that the phosphoric acid is produced in situ.
- the mixture of monopotassium phosphate and dipotassium phosphate is a most valuable fertilizer by itself, having a K 2 0 to P 2 0 5 ratio of 1:1, and being completely water soluble.
- part of the dicalcium phosphate resulted after the neutralization can be used in the step of desulphating the solution obtained in step (a), the chemical reaction (8), being involved in this case.
- the last step of the process involves the crystallization of the monopotassium phosphate from the solution containing it. This is a well known operation which is based on generation of crystals of monopotassium phosphate by changing the solubility of the salt as a function of temperature.
- the monopotassium phosphate When a cold crystallization is carried out, the monopotassium phosphate will be very pure, being substantially free from any cation or anion impurity.
- the monopotassium phosphate obtained in the process according to the present invention is characterized by its high purity since most of the impurities precipitate out and are removed with the gypsum produced in step (a) or with the dicalcium phosphate separated in step (b). It was found that the presence of dicalcium phosphate assists the filtration of the metal impurities, which generally possess bad filtration properties in view of their gelatinous characteristics.
- a typical analysis of the monopotassium phosphate crystals which are obtained in the process is as follows:
- the monopotassium phosphate obtained can be easily transformed into a P-K liquid fertilizer (0-20-20) by its reaction with a solution of potassium hydroxide according to the following equation (11):
- the mixture was agitated for an additional hour.
- an additional amount of 182.6 g of the same phosphate rock (cyclone source) and 25 g of the same phosphoric acid were added and the agitation continued for an additional hour.
- the mixture amounting to 2740 g was filtered; the filter cake consisting mainly of calcium sulfate hydrate was washed by 3 portions of 600 mls water obtaining an amount of 865 g of washed filter cake (22.4% humidity).
- the analysis of the cake (on dry basis) was as follows:
- the mixture was agitated for an additional hour and subsequently an additional amount of 184.7 g of the same phosphate rock and 25.2 g of the same phosphoric acid were added.
- the mixture was filtered after 1 hour on a Buchner filter kept at 70 degrees C.
- the filter cake consisting of calcium sulfate, was washed with 3 portions of water (600 ml each).
- the filter cake of dicalcium phosphate had the following analysis:
- the filtrate had the following composition:
- step a To the other portion of filtrate (obtained in step a) an amount of 180 g of the above washed dicalcium phosphate (40% humidity) and 214 g of a solution of monopotassium sulfate (40% concentration) were added during 30 minutes at 70 degrees C. After about 1 hour, the resulting slurry was filtered on a Buchner heated at 70 degrees centigrade. The resulting slurry had the following composition:
- the washed filter cake resulted thereof had the following analysis:
- reaction mixture was agitated for an additional hour.
- an amount of 256 g of the same phosphate rock (Arad) was added.
- an amount of 82 g of dicalcium phosphate dihydrate (40.9% P 2 0 5 ) was added to 3,860 g of the slurry resulted above maintaining 70 degrees C.
- the cake of calcium sulfate was filtered out on a heated Buchner (at 70 degrees centigrade) and washed with 3 equal portions of 860 ml water (heated at 70 degrees centigrade).
- the amount of washed cake was 1,276 g (32.6% moisture) and the amount of filtrate was 2,230 g.
- the cold crystallization does produce a very pure product.
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
- Saccharide Compounds (AREA)
- Fertilizers (AREA)
- Seasonings (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT86304442T ATE52238T1 (de) | 1985-07-10 | 1986-06-10 | Verfahren zur herstellung von kaliumdihydrogenphosphat. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| IL75767A IL75767A (en) | 1985-07-10 | 1985-07-10 | Process for the manufacture of pure monopotassium phosphate |
| IL75767 | 1985-07-10 |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0208422A2 EP0208422A2 (en) | 1987-01-14 |
| EP0208422A3 EP0208422A3 (en) | 1987-04-01 |
| EP0208422B1 true EP0208422B1 (en) | 1990-04-25 |
Family
ID=11056061
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP86304442A Expired - Lifetime EP0208422B1 (en) | 1985-07-10 | 1986-06-10 | Process for the manufacture of monopotassium phosphate |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US4678649A (no) |
| EP (1) | EP0208422B1 (no) |
| JP (1) | JPH0733244B2 (no) |
| AT (1) | ATE52238T1 (no) |
| AU (1) | AU585027B2 (no) |
| CA (1) | CA1326753C (no) |
| DE (1) | DE3670624D1 (no) |
| IL (1) | IL75767A (no) |
| NO (1) | NO169885C (no) |
| ZA (1) | ZA864431B (no) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5114460A (en) * | 1988-10-31 | 1992-05-19 | Alpine Plant Foods Limited | Production of low-chloride alkali metal phosphates |
| GB8825390D0 (en) * | 1988-10-31 | 1988-11-30 | Univ Waterloo | Production of chloride-free fertilizers-11 |
| FI107330B (fi) * | 1999-12-03 | 2001-07-13 | Kemira Agro Oy | Kahden alkalimetallisuolan valmistaminen yhdistetyllä ioninvaihto- ja kiteytysmenetelmällä |
| US7374740B2 (en) * | 2005-03-31 | 2008-05-20 | Cargill, Incorporated | Process for producing high purity phosphates |
| IL174212A (en) * | 2006-03-09 | 2011-09-27 | Rotem Amfert Negev Ltd | Solid, soluble and soluble fertilizers, free flow and preparation |
| RU2682549C1 (ru) * | 2017-10-13 | 2019-03-19 | Федеральное государственное унитарное предприятие "Институт химических реактивов и особо чистых химических веществ Национального исследовательского центра "Курчатовский институт" | Способ очистки растворов калия дигидрофосфата |
| WO2021203123A1 (en) | 2020-03-31 | 2021-10-07 | Johnson Matthey Public Limited Company | Phosphate salts manufacturing processes |
| CN112758906A (zh) * | 2020-12-31 | 2021-05-07 | 谢坪 | 磷酸二氢钾的生产工艺 |
| CN114057172B (zh) * | 2021-12-29 | 2023-01-20 | 山东省神农生态科技股份有限公司 | 玉米浆中钾离子回收生产磷酸二氢钾的方法及其生产的磷酸二氢钾 |
| CN115676788B (zh) * | 2022-10-18 | 2024-02-02 | 新希望化工投资有限公司 | 一种高纯磷酸二氢钾及其制备方法 |
| CN115535979B (zh) * | 2022-10-18 | 2023-08-08 | 新希望化工投资有限公司 | 一种磷酸二氢钾及利用磷酸氢钙制备磷酸二氢钾的方法 |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US29458A (en) * | 1860-08-07 | petefls | ||
| NL216767A (no) * | 1956-05-01 | |||
| GB1203444A (en) * | 1967-03-07 | 1970-08-26 | Albright & Wilson Mfg Ltd | Production of potassium dihydrogen phosphate |
| US3600152A (en) * | 1968-08-27 | 1971-08-17 | Pennzoil United Inc | Phosphate fertilizer products |
| IE34022B1 (en) * | 1968-09-20 | 1975-01-08 | Goulding Ltd W & H M | The production of fertilisers |
| US3803884A (en) * | 1969-01-09 | 1974-04-16 | Fitzwilton Ltd | Production of fertilizers |
| US3956464A (en) * | 1970-10-16 | 1976-05-11 | Pennzoil Company | Preparation of phosphates |
| US3697246A (en) * | 1970-10-16 | 1972-10-10 | Pennzoil United Inc | Potassium phosphate manufacture |
| US4191734A (en) * | 1976-06-15 | 1980-03-04 | Pennzoil Company | Fluoride-free phosphate reactions |
| US4160657A (en) * | 1978-01-19 | 1979-07-10 | Pennzoil Company | Preparation of monocalcium phosphate and phosphoric acid |
| AU568132B2 (en) * | 1983-06-24 | 1987-12-17 | Thomas, G. | Alkali metal phosphates |
-
1985
- 1985-07-10 IL IL75767A patent/IL75767A/xx not_active IP Right Cessation
-
1986
- 1986-06-06 US US06/872,061 patent/US4678649A/en not_active Expired - Lifetime
- 1986-06-10 DE DE8686304442T patent/DE3670624D1/de not_active Expired - Lifetime
- 1986-06-10 EP EP86304442A patent/EP0208422B1/en not_active Expired - Lifetime
- 1986-06-10 AT AT86304442T patent/ATE52238T1/de not_active IP Right Cessation
- 1986-06-11 CA CA000511309A patent/CA1326753C/en not_active Expired - Fee Related
- 1986-06-13 ZA ZA864431A patent/ZA864431B/xx unknown
- 1986-06-16 AU AU58895/86A patent/AU585027B2/en not_active Expired
- 1986-07-09 JP JP61159872A patent/JPH0733244B2/ja not_active Expired - Fee Related
- 1986-07-09 NO NO862783A patent/NO169885C/no not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| AU585027B2 (en) | 1989-06-08 |
| NO862783D0 (no) | 1986-07-09 |
| IL75767A (en) | 1988-09-30 |
| NO862783L (no) | 1987-01-12 |
| DE3670624D1 (de) | 1990-05-31 |
| CA1326753C (en) | 1994-02-08 |
| EP0208422A2 (en) | 1987-01-14 |
| NO169885B (no) | 1992-05-11 |
| JPS6212603A (ja) | 1987-01-21 |
| US4678649A (en) | 1987-07-07 |
| EP0208422A3 (en) | 1987-04-01 |
| NO169885C (no) | 1992-08-19 |
| JPH0733244B2 (ja) | 1995-04-12 |
| IL75767A0 (no) | 1985-11-29 |
| ATE52238T1 (de) | 1990-05-15 |
| ZA864431B (en) | 1987-02-25 |
| AU5889586A (en) | 1987-01-15 |
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